Buggy code:
public class FileFilterTestCase extends FileBasedTestCase { static final String SVN_DIR_NAME = ".svn" ; private static final boolean WINDOWS = ( File . separatorChar ) == '\\' ; public FileFilterTestCase ( String name ) { } @ Override public void setUp ( ) { } @ Override public void tearDown ( ) throws Exception { } public void assertFiltering ( IOFileFilter filter , File file , boolean expected ) throws Exception { } public void testSuffix ( ) throws Exception { } public void testSuffixCaseInsensitive ( ) throws Exception { } public void testDirectory ( ) throws Exception { } public void testFiles ( ) throws Exception { } public void testPrefix ( ) throws Exception { } public void testPrefixCaseInsensitive ( ) throws Exception { } public void testNameFilter ( ) throws Exception { } public void testNameFilterNullArgument ( ) throws Exception { } public void testNameFilterNullArrayArgument ( ) throws Exception { } public void testNameFilterNullListArgument ( ) throws Exception { } public void testTrue ( ) throws Exception { } public void testFalse ( ) throws Exception { } public void testNot ( ) throws Exception { } public void testAnd ( ) throws Exception { } public void testOr ( ) throws Exception { } public void testFileFilterUtils_and ( ) throws Exception { } public void testFileFilterUtils_or ( ) throws Exception { } @ SuppressWarnings ( "deprecation" ) public void testDeprecatedWildcard ( ) throws Exception { } public void testWildcard ( ) throws Exception { } public void testDelegateFileFilter ( ) throws Exception { } public void testMakeCVSAware ( ) throws Exception { } public void testMakeSVNAware ( ) throws Exception { } public void testAgeFilter ( ) throws Exception { } public void testSizeFilter ( ) throws Exception { } public void testHidden ( ) throws Exception { } public void testCanRead ( ) throws Exception { } public void testCanWrite ( ) throws Exception { } public void testEmpty ( ) throws Exception { } public void testMakeDirectoryOnly ( ) throws Exception { } public void testMakeFileOnly ( ) throws Exception { } public void testMagicNumberFileFilterBytes ( ) throws Exception { } public void testMagicNumberFileFilterBytesOffset ( ) throws Exception { } public void testMagicNumberFileFilterString ( ) throws Exception { } public void testMagicNumberFileFilterStringOffset ( ) throws Exception { } public void testMagicNumberFileFilterValidation ( ) { try { new MagicNumberFileFilter ( ( ( String ) ( null ) ) , 0 ) ; fail ( ) ; } catch ( IllegalArgumentException iae ) { } try { <START_BUG> new MagicNumberFileFilter ( ( ( String ) ( "" ) ) , ( - 1 ) ) ; <END_BUG> fail ( ) ; } catch ( IllegalArgumentException iae ) { } try { new MagicNumberFileFilter ( "" , 0 ) ; fail ( ) ; } catch ( IllegalArgumentException iae ) { } try { new MagicNumberFileFilter ( ( ( byte [ ] ) ( null ) ) , 0 ) ; fail ( ) ; } catch ( IllegalArgumentException iae ) { } try { new MagicNumberFileFilter ( new byte [ ] { 0 } , ( - 1 ) ) ; fail ( ) ; } catch ( IllegalArgumentException iae ) { } try { new MagicNumberFileFilter ( new byte [ ] { } , 0 ) ; fail ( ) ; } catch ( IllegalArgumentException iae ) { } } public void testFilterArray ( ) throws Exception { } public void testFilterArray_fromList ( ) throws Exception { } public void testFilterArrayNullParameters ( ) throws Exception { } public void testFilterList ( ) throws Exception { } public void testFilterList_fromArray ( ) throws Exception { } public void testFilterListNullParameters ( ) { } public void testFilterSet ( ) throws Exception { } public void testFilterSet_fromArray ( ) throws Exception { } public void testFilterSetNullParameters ( ) { } public void testEnsureTestCoverage ( ) { } public void testNullFilters ( ) { } public void testDelegation ( ) { } }

Fix:
new MagicNumberFileFilter ( "0" , ( - 1 ) ) ;